Recently, novel high viscosity index (V.I.) lubricant compositions comprising polyalpha-olefins produced with reduced chromium oligomerization catalysts have been disclosed in U.S. Pat. Nos. 4,827,064 and 4,827,073, to which reference is made for a description of these materials and of their preparation. These materials, referred to as HVI-PAO (High Viscosity Index--Poly Alpha Olefins) are made by contacting a C.sub.6-C.sub.20 1-alkene feedstock with reduced valence state chromium oxide catalyst on porous silica support under oligomerizing conditions. The high viscosity index liquid hydrocarbon lubricants produced have branch ratios less than 0.19 and pour point below -15.degree. C. Lubricants produced by the process cover the full range of lubricant viscosities and exhibit a remarkably high VI and low pour point even at high viscosity. The molecular structure of HVI-PAO is novel, comprising the product of an essentially regular head to tail polymerization of alpha-olefin and providing an oligomer with large pendant alkyl groups on the recurring polymeric unit. The oligomer as formed is particularly characterized by containing a large proportion of terminal olefinic groups, i.e., vinylidenic groups.
Notwithstanding their generally superior properties, HVI-PAO lubricants, as well as other lubricants, are often formulated with additives, or an additive package, to enhance those properties for specific applications. The more commonly used additives include oxidation inhibitors, rust inhibitors, metal passivators, antiwear agents, extreme pressure additives, pour point depressants, detergent-dispersants, viscosity index (VI) improvers, foam inhibitors and the like, as described in Kirk-Othmer "Encyclopedia of Chemical Technology", 3rd edition Vol. 14, pp. 477-526.
Borated additive compositions can be prepared which provide superior dispersant and antioxidant activity in lubricants. In U.S. Pat. No. 4,698,169 to Andress, et al., a process is described for the production of superior additives by reacting an alkenylsuccinic compound with an arylamine and an alkanolamine, an aminomethane or a hindered alcohol, and boric acid. The alkenylsuccinic compound is typically derived as an adduct of an alkenyl compound and maleic anhydride wherein the alkenyl compound contains internal olefinic unsaturation.
U.S. Pat. No. 4,219,431 is directed to lubricant compositions containing a lubricant and a minor amount of a derivative of alkenylsuccinic anhydride which includes the reaction product of (1) an alkenylsuccinic acid, ester or anhydride and a hydroxy aromatic compound and (2) the product of reaction between (1) and an amine, (3) the reaction product of (2) and an aldehyde and (4) the reaction product of (3) and a metal salt.
U.S. Pat. No. 4,803,004 discloses dispersant additives made from an alkenyl (succinic compound by reaction with an arylamine and a hindered alcohol.